Multi-speed transaxle for electric and hybrid vehicle application

ABSTRACT

An electric drive module for transferring torque to wheels of a motor vehicle a planetary gearset having a first member driven by the rotor and a second member. A synchronizer restricts a third member of the planetary gearset from rotation when the electric drive module operates at a first drive ratio. The synchronizer transfers energy from the rotating rotor to the third member during a shift between the first drive ratio and a second drive ratio to match the rotational speeds of the rotor and the second member. A reduction unit includes an input member being driven by the second member and also includes an output member driven at a reduced speed relative to the input member. A differential assembly includes an input driven by the output member, a first differential output driving a first output shaft, and a second differential output driving a second output shaft.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/426,856, filed on Dec. 23, 2010. The entire disclosure of the above application is incorporated herein by reference.

FIELD

The present disclosure relates to electric drive systems for motor vehicles. More specifically, the present disclosure relates to a two-speed electric drive module for electric and hybrid vehicles.

BACKGROUND

Automobile manufacturers are actively working to develop alternative powertrain systems in an effort to reduce the level of pollutants exhausted into the air by conventional vehicles equipped with internal combustion engines. Significant development has been directed to electric vehicles and fuel cell vehicles. These alternative powertrain systems are still under development. In addition, several different hybrid electric vehicles have recently been offered for sale. These hybrid vehicles are typically equipped with an internal combustion engine and an electric motor that can be operated independently or in combination to drive the vehicle.

There are two common types of hybrid vehicles, namely, series hybrid and parallel hybrid. In a series hybrid vehicle, power is delivered to the wheels by the electric motor which draws electrical energy from the battery. The engine is used in series hybrid vehicles to drive a generator which supplies power directly to the electric motor or charges the battery when the state of charge falls below a predetermined value. In parallel hybrid vehicles, the electric motor and the engine can be operated independently or in combination pursuant to the running conditions of the vehicle. Typically, the control strategy for such parallel hybrid vehicles defines a low-load mode where only the electric motor is used to drive the vehicle, a high-load mode where only the engine is used to drive the vehicle, and an intermediate assist mode where the engine and electric motor are both used to drive the vehicle. Regardless of the type of hybrid drive system used, hybrid vehicles are highly modified versions of conventional vehicles that are expensive due to the componentry, required control systems, and specialized packaging requirements.

Hybrid powertrains have also been adapted for use in four-wheel drive vehicles and typically utilize the above-noted parallel hybrid powertrain to drive the primary wheels and a second electric motor to drive the secondary wheels. Obviously, such a four-wheel drive system is extremely expensive and difficult to package. Thus, a need exists to develop solely electrically powered or hybrid powertrains for use in various types of vehicles.

SUMMARY

An electric drive module for transferring torque to wheels of a motor vehicle a planetary gearset having a first member driven by the rotor and a second member. A synchronizer restricts a third member of the planetary gearset from rotation when the electric drive module operates at a first drive ratio. The synchronizer transfers energy from the rotating rotor to the third member during a shift between the first drive ratio and a second drive ratio to match the rotational speeds of the rotor and the second member. A reduction unit includes an input member being driven by the second member and also includes an output member driven at a reduced speed relative to the input member. A differential assembly includes an input driven by the output member, a first differential output driving a first output shaft, and a second differential output driving a second output shaft.

An electric drive module for transferring torque to wheels of a motor vehicle includes an electric motor having a rotatable rotor. A first input member is driven by the rotor. A two-speed module drivingly interconnects the first input member and a first output member at one of two different drive ratios. The two-speed module includes a planetary gearset and a synchronizer. The synchronizer restricts one member of the planetary gearset from rotation when the two-speed module operates at a first drive ratio. The synchronizer transfers energy from the rotating rotor during a shift between the first drive ratio and a second drive ratio to match the rotational speeds of the rotor and the first output member. A reduction unit includes a second input member being driven by the first output member and further includes a second output member being driven at a reduced speed relative to the second input member. A differential assembly has an input driven by said second output member, a first differential output driving a first output shaft, and a second differential output driving a second output shaft.

Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present disclosure, are intended for purposes of illustration only since various changes and modifications within the fair scope of this particular disclosure will become apparent to those skilled in the art.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a schematic view showing a hybrid powertrain for a four-wheel drive vehicle in accordance with the present disclosure;

FIG. 2 is a schematic view of an alternative arrangement for the hybrid powertrain of the present disclosure;

FIG. 3 is a schematic view of an alternative arrangement electric powertrain of the present disclosure;

FIG. 4 is a sectional view of an electric drive module associated with the powertrains of FIGS. 1-3;

FIG. 5 is a sectional view of an alternate electric drive module;

FIG. 6 is a fragmentary end view of a compound planetary gearset of the electric drive module shown in FIG. 5.

FIG. 7 is sectional view of another alternate electric drive module; and

FIG. 8 is a sectional view of another alternate electric drive module.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings.

The present disclosure is related to an electric drive module assembly including an electric motor. The electric drive module is electrically-controlled for delivering motive power (i.e., drive torque) to a pair of ground-engaging wheels. The compact arrangement of the electric motor and a two-speed gearbox permits the use of the electric drive module in substitution for a conventional axle assembly. As such, conventional rear-wheel drive and front-wheel drive powertrains can be used in combination with the electric drive module so as to establish a hybrid drive system for a four-wheel drive vehicle. Alternatively, the electric drive module may be used in vehicles powered solely by batteries as well. Accordingly, various features and functional characteristics of the electric drive module will be set forth below in a manner permitting those skilled in relevant arts to fully comprehend and appreciate the significant advantages the present disclosure provides.

Referring to FIG. 1, a four-wheel drive powertrain for a hybrid electric vehicle 10 is shown to include a first powered driveline 12 and a second powered driveline 14. First powered driveline 12 includes an internal combustion engine 16, a transmission 18, a drive shaft 20, and an axle assembly 22 connecting a pair of wheels 24. Engine power is delivered to a differential unit 26 associated with axle assembly 22 through transmission 18 and drive shaft 20. The drive torque delivered to differential unit 26 is transferred through axleshafts 28 and 30 to wheels 24. Second powered driveline 14 includes an electric drive module 32 which drives a second pair of wheels 34 through axleshafts 36 and 40.

In the particular layout shown in FIG. 1, first powered driveline 12 delivers power to rear wheels 24 while second powered driveline 14 delivers power to front wheels 34. Obviously, those skilled in the art would understand that the opposite powertrain arrangement can be utilized such that electric drive module 32 supplies power to the rear wheels. To better illustrate this arrangement, FIG. 2 shows module 32 supplying power to rear wheels 24 through axleshafts 28 and 30 while engine power is supplied to front wheels 34 through a transaxle 18A and axleshafts 36 and 40. Regardless of the particular arrangement, hybrid vehicle 10 includes two distinct powered drivelines capable of both independent and combined operation to drive the vehicle.

As shown in FIG. 3, it is also contemplated that electric drive module 32 may be the sole source of motive power for vehicle 10. An internal combustion engine would not be present. Accordingly, front wheels 34 receive torque through axleshafts 36 and 40 provided by electric drive module 32.

Referring now to FIG. 4, electric drive module 32 will be described in detail. Electric drive module 32 includes a multi-section housing assembly 42 defining a motor chamber 44 and a gearbox chamber 46 separated by a radial support wall 48. Electric drive module 32 is depicted as a two-speed transaxle. An electric variable speed motor assembly 58 is located within motor chamber 44 and includes a wound stator 60 secured to housing assembly 42. and a rotatable rotor 61. An elongated tubular rotor shaft 62 is supported at its opposite ends by bearing assemblies 64 for rotation relative to housing assembly 42. Rotor assembly 61 is fixed for rotation with rotor shaft 62.

Electric drive module 32 further includes a gearbox 68 located within gearbox chamber 46 and which is comprised of planetary gearset 69, a reduction unit 70 and a bevel differential 72. A synchronizer assembly 73 is associated with both planetary gearset 69 and reduction unit 70. Reduction unit 70 includes a first reduction gearset 74 having a first drive gear 76 in constant meshed engagement with a first driven gear 78 as well as a second reduction gearset 80 having a second drive gear 82 in constant meshed engagement with a second driven gear 84. First drive gear 76 is fixed for rotation with a transfer shaft 86. First driven gear 78 and second drive gear 82 are fixed for rotation with an intermediate shaft 88 rotatably supported by bearings 90. Second driven gear 84 is fixed to a casing 94 of bevel differential 72.

Bevel differential 72 includes a pair of bearings 100 rotatably supporting bell-shaped casing 94. Bevel differential 72 further includes a first side gear 108 fixed via a spline connection 110 to a first output shaft 112, a second side gear 114 fixed via a spline connection 116 to a second output shaft 118, and at least one pair of pinions 120 meshed with side gears 108 and 114. Pinions 120 are rotatably supported on a pinion shaft 122 having its opposite ends located in polar apertures 124 formed in casing 94.

Planetary gearset 69 includes a sun gear 130, an annulus gear 132, and a plurality of pinion gears 134 positioned in constant meshed engagement with sun gear 130 and annulus gear 132. A carrier 136 includes pinion shafts 138 rotatably supporting pinion gears 134. Annulus gear 132 is fixed for rotation with rotor shaft 62 via a splined coupler 140 and a plate 142.

Sun gear 130 is integrally formed with a hollow input shaft 146. Hollow input shaft 146 passes through hollow transfer shaft 86 and synchronizer assembly 73. Bearings 148, 150 rotatably support input shaft 146. Carrier 136 is fixed for rotation via splined engagement with transfer shaft 86 and first drive gear 76.

Synchronizer assembly 73 includes a hub 156 fixed for rotation with input shaft 146. Synchronizer assembly 73 includes a shift sleeve 158 mounted for rotation with hub 156 by means of an externally splined surface being in sliding meshed engagement with an internal spline surface of sleeve 158. Synchronizer assembly 73 also includes blocker rings 160, 162, cone rings 164, 166, a first drive member 170 and a second drive member 172. A shift fork 174 cooperates with shift sleeve 158 to axially translate shift sleeve 158 between a first position drivingly engaged with first member 170, a neutral position as shown in upper portion of FIG. 1, and a second position drivingly engaged with second member 172. First member 170 is fixed to housing assembly 42 and is restricted from rotation. Second member 172 is fixed for rotation with transfer shaft 86.

A shift mechanism 176 includes an actuator 178 operable to axially translate shift fork 174. Actuator 178 may include any number of components including linear feed screw arrangements, electric motors, hydraulic motors, cams, ball ramp actuators and the like.

A parking pawl assembly 180 is provided to selectively ground a parking gear 182 fixed for rotation with intermediate shaft 88 to housing assembly 42. Parking gear 182 includes a plurality of teeth 184 selectively engageable with a parking pawl 186. When parking pawl 186 is engaged with teeth 184, rotation of the components within reduction unit 70 is restricted. Accordingly, movement of vehicle 10 is also restricted. Parking pawl 186 may be rotated to become engaged and disengaged from teeth 184. When parking pawl 186 is disengaged from teeth 184, the components within reduction unit 70 may rotate as previously described.

In accordance with a use of electric drive module 32, output shafts 112 and 118 are adapted to be connected to corresponding ones of front axleshafts 36 and 40 for the hybrid powertrain arrangement shown in FIG. 1 or, alternatively, to corresponding ones of rear axleshafts 28 and 30 for the powertrain arrangement shown in FIG. 2. In this manner, electric drive module 32 functions as an electrically-powered axle assembly which can be controlled independently, or in combination with, the engine-based powertrain.

Two-speed gearbox 68 includes planetary gearset 69 and synchronizer assembly 73 acting in cooperation with one another to selectively provide one of a first gear ratio (low) and a second gear ratio (high) between rotor shaft 62 and transfer shaft 86. Actuator 178 axially translates shift fork 174 and shift sleeve 158 to a right-most position when viewed in FIG. 4 where hub 156 is fixed for rotation with first member 170 via shift sleeve 158 as shown in the lower portion of FIG. 4. At this first or low position, hub 156, input shaft 146 and sun gear 130 are restricted from rotation. Input torque provided by electric motor assembly 58 is transferred through rotor shaft 62 and input to annulus gear 132. Carrier 136 acts as the output rotating at a reduced speed relative to rotor shaft 62. Because electric drive module 32 is only operable in two different drive ratios, the low gear ratio is significantly spaced apart from the high gear ratio. To achieve desirable vehicle performance, rotor 61 and rotor shaft 62 rotate at relatively high rotational speeds immediately prior to shifting from the low gear range to the high gear range.

During the shift, a significant challenge exists regarding reducing the rotational speed of rotor 61 and rotor shaft 62 due to the relatively high inertia of these members. At the same time, sun gear 130, input shaft 146 and hub 156 are accelerated from a zero rotational speed to the new desired rotor shaft speed. Furthermore, care must be taken to maintain the rotational speed of carrier 136 and the downstream components of reduction unit 70 to allow the vehicle wheels to rotate at the same speed before and after the gear shift.

Synchronizer assembly 73 and planetary gearset 69 cooperate with one another to exert a mechanical advantage on rotor shaft 62 and rotor 61 during the shift from the first gear ratio to the second gear ratio. More particularly, actuator 178 axially translates shift sleeve 158 to the neutral position shown at the top portion of FIG. 4 to free sun gear 130 for rotation. Actuator 178 continues to axially translate shift sleeve 158 toward the left to frictionally engage cone clutch portions of blocker ring 160 and cone ring 164. At this time, torque is transferred through second member 172 to carrier 136. Carrier 136 now acts as the input member of planetary gearset 69 and annulus gear 132 acts as the output member. A mechanical advantage is provided to reduce the speed of rotor shaft 62. Once the speeds of annulus gear 132 and sun gear 130 are substantially matched, blocker ring 160 rotates to allow shift sleeve 158 to fully axially translate to the left and rotationally fix hub 156 for rotation with second member 172. At this time, sun gear 130 and annulus gear 132 are also fixed for rotation with one another. Planetary gearset 69 is locked such that a direct drive or 1:1 ratio is provided from rotor shaft 62 to transfer shaft 86. Electric drive module 32 now operates in the second gear ratio.

As shown in FIGS. 1-3, a controller 190 is in communication with a battery 192, vehicle sensors 194, electric drive module 32 as well as the engine and transmission, if present. Concurrent control of engine 16, transmission 18 and electric drive module 32 is described in issued U.S. Pat. Nos. 6,595,308 and 6,604,591, which are herein incorporated by reference.

In relation to the two-speed arrangement, controller 190 is operable to control shift mechanism 176 and execute an upshift from LOW to HIGH or a downshift from HIGH to LOW, as desired. Controller 190 may also place electric drive module 32 in a regeneration mode such that energy from vehicle 10 may be used to charge battery 192 during a vehicle descent or braking event.

FIGS. 5 and 6 depict another electric drive module identified at reference numeral 200. Electric drive module 200 is substantially similar to electric drive module 32. As such, similar elements will be identified with like reference numerals including a lower “a” suffix. The main difference between electric module 200 and electric drive module 32 relates to a planetary gearset 202 replacing planetary gearset 69. Planetary gearset 202 is configured as a dual-planet star epicyclic gearset where planetary gearset 69 is arranged as a solar epicyclic arrangement. Planetary gearset 202 includes a sun gear 204 fixed for rotation with rotor shaft 62 a. An annulus gear 206 is fixed for rotation with transfer shaft 86 a. A carrier 208 is fixed for rotation with input shaft 146 a. Planetary gearset 202 includes first planet gears 210 circumferentially spaced apart from one another and in constant meshed engagement with annulus gear 206. First planet gears 210 are spaced apart from sun gear 204. Second planet gears 212 are circumferentially spaced apart from one another and meshingly engaged with both sun gear 204 and a respective one of first planet gears 210. Second planet gears 212 do not engage annulus gear 206. The remaining components of electric drive module 200 are substantially similar to those previously described in relation to electric drive module 32.

During operation of electric drive module 200, low gear may be provided by translating shift fork 174 a and shift sleeve 158 a to the right to restrict rotation of input shaft 146 a and carrier 208. Drive torque is provided from motor assembly 58 a through rotor shaft 62 a to the input or sun gear 204 of planetary gearset 202. Annulus gear 206 functions as the output and provides multiplied torque to transfer shaft 86 a. In the shift from first gear to second gear, synchronizer assembly 73 a decreases the rotational speed of rotor shaft 62 a and increases the speed of input shaft 146 a and carrier 308 until the speeds are matched and the 1-2 shift may be completed.

FIG. 7 depicts another alternate electric drive module identified at reference numeral 300. Electric drive module 300 is substantially similar to electric drive modules 32 and 200. Accordingly, similar elements will be identified with like reference numerals including a “b” suffix. Electric drive module 300 includes a planetary gearset 302 differing from the planetary gearsets previously described. In particular, planetary gearset 302 is a dual-planet inverted solar arrangement. A carrier 304 is fixed for rotation with rotor shaft 62 b. An annulus gear 306 is fixed for rotation with transfer shaft 86 b. A sun gear 308 is integrally formed with input shaft 146 b. First planet gears 310 are meshingly engaged with annulus gear 306 and spaced apart from sun gear 308. Second planet gears 312 are meshingly engaged with first planet gears 310 and sun gear 308. Second planet gears 312 are spaced apart from annulus gear 306.

A first low gear is provided by grounding sun gear 306 and input shaft 146 b to housing assembly 42 b via synchronizer 73 b. As with the earlier embodiments previously described, this accomplished by axially translating shift sleeve 158 b to the right as shown in FIG. 7. Input torque is transferred from rotor shaft 62 b to carrier 304. A reduced speed output is provided from annulus gear 306 to transfer shaft 86 b.

During a shift from low gear to high gear, synchronizer 73 b is actuated causing shift sleeve 158 b to translate to the left and frictionally engage blocker ring 160 b and cone ring 164 b. Energy is transferred between the high inertia rotating mass of rotor 61 b and the previously stationary mass of hub 156 b, input shaft 146 b and sun gear 308 via planetary gearset 302. Planetary gearset 302 is arranged such that a mechanical advantage is provided to synchronizer 73 b during the shift from low gear to high gear. During the shift, the input is sun gear 308 and carrier 304 is the output as planetary gearset 302 functions to reduce the speed of rotor shaft 62 b and rotor 61 b. Once the rotational speeds of rotor shaft 62 b and carrier 304 match the rotational speed of sun gear 308 and input shaft 146 b, shift sleeve 158 b may be axially translated to the left to provide the second gear ratio.

FIG. 8 depicts another alternate electric drive module identified at reference numeral 400. Electric drive module 400 is substantially similar to the previously described drive modules and similar elements will be identified with like numerals having a “d” suffix. Electric drive module 400 includes a planetary gearset 402 arranged as a dual-sun, dual-planet epicyclic configuration. Planetary gearset 402 includes a first sun gear 404 fixed for rotation with rotor shaft 62 d. A carrier 406 is fixed for rotation with transfer shaft 86 d. First pinions 408 are rotatably supported on first pins 410. Each of first pinions 408 is meshingly engaged with first sun gear 404. Second pinions 412 are rotatably supported on second pins 414. Second pinions 412 are meshingly engaged with first pinions 408 and a second sun gear 416. Second sun gear is fixed for rotation with input shaft 146 d. First pinions 408 are substantially longer than second pinions 412 to axially extend a distance to simultaneously engage first sun gear 404 and second pinions 412. In the dual-sun, dual-planet epicyclic gearset depicted, an annulus gear is not present.

Second sun gear 416 is restricted from rotation when shift sleeve 158 d is in the rightmost position. Torque is provided from electric motor assembly 58 d through rotor shaft 62 d to first sun gear 404. Planetary gearset 402 outputs torque through carrier 406 to transfer shaft 86 d.

During a shift from low gear to high gear, second sun gear 416 functions as the input of planetary gearset 402 while first sun gear 404 functions as the output. As such, synchronizer 73 d is provided a mechanical advantage equal to the gear ratio provided by planetary gearset 402 when operated in this manner. The relatively high inertia rotor 61 d rotating at a relatively high speed may be rapidly decelerated to match the rotational speed of input shaft 146 d. Shift sleeve 158 is transferred to the left to provide the second gear ratio.

Electric drive module 400 further differs from those previously described in that a park gear 420 is fixed for rotation with transfer shaft 86 d. A park pawl 422 may be positioned in selective engagement with teeth 424 formed on parking gear 420 to restrict the members of reduction unit 70 d and first and second output shafts 112 d, 118 d.

The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 

What is claimed is:
 1. An electric drive module for transferring torque to wheels of a motor vehicle, comprising: an electric motor including a rotatable rotor; a first input member driven by the rotor; a first output member; a two-speed module drivingly interconnecting the first input member and the first output member at one of two different drive ratios, the two-speed module including a planetary gearset and a synchronizer, the synchronizer being operable to restrict one member of the planetary gearset from rotation when the two-speed module operates at a first drive ratio, the synchronizer transferring energy from the rotating rotor during a shift between the first drive ratio and a second drive ratio to match the rotational speeds of the rotor and the first output member; a reduction unit including a second input member being driven by the first output member and further including a second output member being driven at a reduced speed relative to the second input member; and a differential assembly having an input driven by said second output member, a first differential output driving a first output shaft, and a second differential output driving a second output shaft.
 2. The electric drive module of claim 1, further including an input shaft interconnecting the one member of the planetary gearset and the synchronizer, the input shaft extending through the first output member.
 3. The electric drive module of claim 2, wherein the synchronizer directly drivingly interconnects the input shaft and the first output shaft for same speed rotation when the second drive ratio is provided.
 4. The electric drive module of claim 1, wherein the reduction unit includes a first drive gear fixed for rotation with the first output member, a first driven gear and a second drive gear fixed for rotation with an intermediate shaft and a second driven gear fixed for rotation with the differential assembly input.
 5. The electric drive module of claim 4, wherein the intermediate shaft rotates about an axis substantially parallel to and offset from an axis of rotation of the first input member.
 6. The electric drive module of claim 3, wherein the planetary gearset provides a mechanical advantage to the synchronizer during a shift from the first drive ratio to the second drive ratio to reduce the speed of the rotor.
 7. The electric drive module of claim 1, wherein the first input member is fixed for rotation with an annulus gear of the planetary gearset, the first output member includes a carrier of the planetary gearset, and the one member of the planetary gearset includes a sun gear.
 8. The electric drive module of claim 1, wherein the first input member is fixed for rotation with a sun gear of the planetary gearset, the first output member includes an annulus gear, and the one member of the planetary gearset includes a carrier.
 9. The electric drive module of claim 1, wherein the first input member is fixed for rotation with a carrier of the planetary gearset, the first output member includes an annulus gear, and the one member of the planetary gearset includes a sun gear.
 10. The electric drive module of claim 1, wherein the first input member is fixed for rotation with a first sun gear of the planetary gearset, the first output member includes a carrier, and the one member of the planetary gearset includes a second sun gear, wherein the planetary gearset includes a first pinion meshingly engaged with the first sun gear and a second pinion, the second pinion also meshingly engaged with the second sun gear.
 11. An electric drive module for transferring torque to wheels of a motor vehicle, comprising: an electric motor including a rotatable rotor; a planetary gearset including a first member driven by the rotor and a second member; a synchronizer operable to restrict a third member of the planetary gearset from rotation when the electric drive module operates at a first drive ratio, the synchronizer transferring energy from the rotating rotor to the third member during a shift between the first drive ratio and a second drive ratio to match the rotational speeds of the rotor and the second member; a reduction unit including an input member being driven by the second member and further including an output member being driven at a reduced speed relative to the input member; and a differential assembly having an input driven by the output member, a first differential output driving a first output shaft, and a second differential output driving a second output shaft.
 12. The electric drive module of claim 11, wherein the synchronizer includes a shift sleeve axially translatable between a first position grounding the third member to a housing and a second position drivingly interconnecting the third member and the second member.
 13. The electric drive module of claim 12, wherein the planetary gearset provides a mechanical advantage to the synchronizer during a shift from the first drive ratio to the second drive ratio to reduce the speed of the rotor.
 14. The electric drive module of claim 13, wherein the first member of the planetary gearset includes an annulus gear, the second member includes a carrier of the planetary gearset, and the third member of the planetary gearset includes a sun gear.
 15. The electric drive module of claim 13, wherein the first member of the planetary gearset includes a sun gear, the second member includes an annulus gear, and the third member of the planetary gearset includes a carrier.
 16. The electric drive module of claim 13, wherein the first member of the planetary gearset includes a carrier, the second member includes an annulus gear, and the third member of the planetary gearset includes a sun gear.
 17. The electric drive module of claim 13, wherein the first member of the planetary gearset includes a first sun gear, the second member includes a carrier, and the third member of the planetary gearset includes a second sun gear, wherein the planetary gearset includes a first pinion meshingly engaged with both of the first sun gear and a second pinion, the second pinion also meshingly engaged with the second sun gear. 